UITableViewCell with UILabel subview caching issue - objective-c

Question

First of all, please don't tell me this is a duplicate. I know this question has been asked and answered many times but I still can't seem to get my code to work even after reading everyone else's solutions.
I'm having an issue with my UITableViewCell that contains a UILabel subview. The UILabel sometimes doesn't appear in certain cells until I scroll away from those cells and return to them. Here is the code I am using to customize the cells:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
UILabel *label;
if (cell == nil) {
// cell is nil, create it
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 50, 33)];
label.tag = 888;
} else {
label = (UILabel*)[cell.contentView viewWithTag:888];
[label removeFromSuperview];
}
label.text = #"Label Text";
label.backgroundColor = [UIColor clearColor];
[label sizeToFit];
label.center = CGPointMake(cell.contentView.frame.size.width-label.frame.size.width/2-20, cell.contentView.frame.size.height/2);
[cell.contentView addSubview:label];
// customize cell text label
cell.textLabel.text = #"Cell Text";
cell.textLabel.textColor = [UIColor darkGrayColor];
return cell;
}
It appears as though the label shows up correctly when dequeueReusableCellWithIdentifier:CellIdentifier returns a non nil value but does not show up if the return value is nil and a new cell must be instantiated.
If anyone has an idea of why this might be happening, help would be greatly appreciated.

Answer 1

I see a couple of things you want to do.
1) read up on "sizeToFit" - the description says if the view has no superview you may get weird results.
2) When you create the view, add it to the cell immediately.
3) After you resize the cell, get its size, then compute the proper frame - I'd suggest not using "center" but I do not know that your code won't work for a fact.
4) Before even changing the center to changing the frame, hard code something like this:
CGRect r = label.frame;
r.origin = (CGPoint){ 20, 20 };
label.frame = r;
This will at least convince you that new cells and old cells are working properly. Then you can compute the frame you really want, or further play with center.

Answer 2

Not sure of the cause of your problem, but there are some improvements you could make. Maybe one of them fixes the issue:
In the dequeu scenario, you remove the label from the view, only to add it back. Instead, you should leave it in the view hierarchy.
To avoid having to resize and move the label all the time. Why not make it sufficiently wide, set the text right aligned. That way, you don't have to resize of move the label in the dequeue scenario.

Answer 3

It seems that the issue may be with modifying cell.textLabel. Other posts on this site have suggested that any time this label is modified, a new label is actually created and added to the cell's contentview (as opposed to just modifying the existing label). Setting cell.textLabel.backgroundColor = [UIColor clearColor]; seems to have fixed the problem
I'm still a bit confused about this though because even adding my custom label subview last (after setting properties for cell.textLabel) didn't fix the problem - the background color of cell.textLabel had to be set to transparent/clear.

Answer 4

There are three things out of place:
if (cell == nil) { // cell is nil, create it
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 50, 33)];
label.tag = 888;
[cell.contentView addSubview:label]; // (1) DO THIS HERE
} else {
label = (UILabel*)[cell.contentView viewWithTag:888];
// (2) DON'T DO THIS: [label removeFromSuperview];
}
label.text = #"Label Text";
label.backgroundColor = [UIColor clearColor];
[label sizeToFit];
label.center = CGPointMake(cell.contentView.frame.size.width-label.frame.size.width/2-20, cell.contentView.frame.size.height/2);
// (3) DON'T DO THIS HERE: [cell.contentView addSubview:label];
....
I assume ARC is on, otherwise you need a [label release] after adding it to the contentView.